Most currently available vaccines consist of killed or live-attenuated pathogens delivered by injection. Despite their success in preventing disease, compelling conceptual, technical and economical reasons exist to seek alternatives to traditional “Jennerian” vaccines.
Vaccines delivered parenterally require injections that must be given by medically trained personnel. Additionally, injection risks possible transmission of infection. Finally, parenteral delivery of vaccines invokes a systemic response, but not a mucosal response.
Subunit vaccines, especially those vaccines that target the mucosal immune system, are viable, safe and effective alternatives. Mucosal vaccines do not require injection; thus, risk of transmission of infection is minimal. Finally, mucosal vaccines elicit immune response both systemically and mucosally.
Additionally, recent breakthroughs suggest that vaccines can be produced in edible tissues of transgenic plants that can then be orally immunogenic. The concept of using transgenic plants as vectors for the production and delivery of edible vaccines has been previously demonstrated.
However, to be effective, mucosal subunit vaccines often need to be co-administered with an “adjuvant.” An “adjuvant” is an immunostimulatory agent that would enhance the specific immune responses against the vaccine candidate.
Therefore, a need exists for an immunostimulatory, mucosally-active composition that can be used as a systemic, mucosal, or epidermal adjuvant.